Where does “fervescendus” come from?

fervescendus (Latin) comes from Latin fervesco, from Latin ferveō, from Proto-Italic ferweō, from Proto-Indo-European bʰrewh₁-, from Proto-Indo-European bʰer- — to bear, carry.

Definitions

Ancestry of “fervescendus”, step by step

Step	Language	Word	Meaning
1	Latin	fervesco	I grow hot; begin to boil
2	Latin	ferveō	to be hot
3	Proto-Italic	ferweō	—
4	Proto-Indo-European	bʰrewh₁-	to boil; to brew
5	Proto-Indo-European	bʰer-	to bear, carry

Every word from Proto-Indo-European bʰer- →Every word from Proto-Indo-European bʰrewh₁- →Every word from Proto-Italic ferweō →